Evaluating the Response of Glycine soja Accessions to Fungal Pathogen Macrophomina phaseolina during Seedling Growth

Charcoal rot caused by the fungal pathogen Macrophomina phaseolina (Tassi) Goid is one of various devastating soybean (Glycine max (L.) Merr.) diseases, which can severely reduce crop yield. The investigation into the genetic potential for charcoal rot resistance of wild soybean (Glycine soja) accessions will enrich our understanding of the impact of soybean domestication on disease resistance; moreover, the identified charcoal rot-resistant lines can be used to improve soybean resistance to charcoal rot. The objective of this study was to evaluate the resistance of wild soybean accessions to M. phaseolina at the seedling stage and thereby select the disease-resistant lines. The results show that the fungal pathogen infection reduced the growth of the root and hypocotyl in most G. soja accessions. The accession PI 507794 displayed the highest level of resistance response to M. phaseolina infection among the tested wild soybean accessions, while PI 487431 and PI 483660B were susceptible to charcoal rot in terms of the reduction in root and hypocotyl growth. The mean values of the root and hypocotyl parameters in PI 507794 were significantly higher (p < 0.05) than those of PI 487431 and PI 483460B. A analysis of the resistance of wild soybean accessions to M. phaseolina using the root and hypocotyl as the assessment parameters at the early seedling stage provides an alternative way to rapidly identify potential resistant genotypes and facilitate breeding for soybean resistance to charcoal rot.